A cordless power tool system is disclosed in WO2006/044693A2. This system comprises a power tool, a battery pack, which can be attached to and detached from the power tool, and a charger, which charges the battery pack.
With such a cordless power tool, an external power supply (e.g., an electrical outlet) is not needed to operate the power tool. Instead, the user needs to charge the battery pack beforehand. The battery pack is charged (recharged) using the charger.
The charger is configured such that the battery pack can be attached to and detached from the charger. When the battery pack is attached, the charger automatically starts charging the battery pack. During the charging of the battery pack, the charger controls the charging current and the charging voltage supplied to the battery pack, while monitoring the temperature and the voltage of the battery pack. When the battery pack reaches a full charge, the charger automatically stops charging the battery pack. During this interval, the user need not take any action to facilitate the charging operation.